@MateoBell what's the provenance of the ITERhybrid_COCOS17_IDS_ddv4.nc file? I'd like to extend it to have multiple time slices so that I can test what I've implemented in this PR.

Linked to #1391. During investigating the different geometry loaders in ST, I am comparing eqdsk from various timesteps with CHEASE, IMAS, etc. Hence, I need to be able to load different slices from the IMAS equilibrium IDS.

@MateoBell what's the provenance of the ITERhybrid_COCOS17_IDS_ddv4.nc file? I'd like to extend it to have multiple time slices so that I can test what I've implemented in this PR.

The .nc file was generated with chease converting the EQDSK_ITERhybrid_COCOS02.eqdsk (actually not completely sure which eqdsk of the examples, but it is the one which was used to compare to the CHEASE default geometry file). There is a script to run CHEASE from an eqdsk and save it to an IDS in a database, and then I converted it in netCDF. The script probably requires IMAS core so I can try to generate an IDS with multiple time slices with given eqdsk if needed.

Thanks! I think for this PR we ideally would have an IDS with different profiles across the time steps we're comparing. This will also pave the way for smoothly interpolating between geometries to have evolving geometry over the run, but this may require rerunning CHEASE (or equivalent fixed-boundary solver) to produce something consistent.

We could, for example, run CHEASE twice using the pprime and FFprime profiles from the beginning and end of the TORAX iterhybrid rampup case as inputs, to give two different geometries for the start and end of the ramp.

What do you think?

We could, for example, run CHEASE twice using the pprime and FFprime profiles from the beginning and end of the TORAX iterhybrid rampup case as inputs, to give two different geometries for the start and end of the ramp.

Yes fully agree ! I think it is a good idea so we can get different geometries at different times to compare.

I've never run CHEASE before, if you're able would you be able to generate the two geometries?

Failing CI is just the placeholder test that's waiting for the new data.

Ok I think I should be able to do it, will try to do it asap !

Thanks both! Having a multiple time-slice IDS loader and a test for it would be ideal

I added the multiple time slices IDS, but I just noticed the netCDF file is pretty heavy. I generated it with CHEASE for all time slices of the output simulation from iterhybrid_rampup config. If needed I can reduce the number of time slices to reduce the weight.
Also I modified a bit the tests to make sure the IDS was generated properly and passing it, I fixed it rapidly so you might want to do it more properly.

Incredible, thanks so much @MateoBell. Your fixes to the tests also seem fine!

In the latest force push I just rebased onto main.

For reference, the full .nc is 56.21 MB (GitHub's recommended limit is 50MB). I think we can definitely reduce the number of timeslices - maybe we should go down to ~10 from ~40?

Thanks both!

~10 from ~40?

Yes, good idea to not load up the repo with large files

Okay just replaced it with 11 time slices evenly spaced in time, the file is now ~16MB !